I have both and both have advantages over the other. Need 1-1 and the 70-300 is a poor choice. Don't want to get a inch from your subject or want the versatility of both telephoto and close up and the 35mm falls short.

Well, of course, but 35 is drastically smaller, more robust and effectively between 1.5 to 12 stops faster (F number and focal length). It definitely depends on what one need lens for, pro&cons, etc..

Aside from using both, I have run the Weekly close up in the summer for years. There I have seen just about every possible way to shoot a close up and there have been shots from people using a 70-300 that are as good as any posted. Honestly I think it is sharper in use as a close up lens than as a telephoto.

I generally dislike 70-300, but for non-critical photography with enough light it is more than enough.